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United States Patent |
5,028,505
|
Akasaki
,   et al.
|
July 2, 1991
|
Electrophotographic photoreceptor
Abstract
An electrophotographic photoreceptor is disclosed, comprising a conductive
substrate having thereon a photosensitive layer, wherein the
photosensitive layer comprises at least one compound selected from the
group consisting of a compound of formula (I), a compound of formula (II),
and a compound of formula (III) as defined below:
##STR1##
wherein X.sup.I represents a cyano group, an alkoxycarbonyl group, or an
aryloxycarbonyl group; R.sup.I.sub.1 and R.sup.I.sub.2 each represents a
hydrogen atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group; A.sup.I represents
##STR2##
wherein R.sup.I.sub.3 and R.sup.I.sub.9 each represents a hydrogen atom,
an alkyl group, a nitro group, a halogen atom, or a cyano group; and m and
n each represents an integer of 0 to 3;
##STR3##
wherein X.sup.II represents O, C(CN).sub.2 or C(CO.sub.2 R.sup.II).sub.2,
wherein R.sup.II is an alkyl group; R.sup.II.sub.1 and R.sup.II.sub.2 each
represents a hydrogen atom, an alkyl group, an aryl group, an
alkoxycarbonyl group, an aryloxycarbonyl group, a nitro group, a halogen
atom, or a cyano group; and m' and n' each represents an integer of 0 to
2; and
##STR4##
wherein R.sup.III.sub.1 and R.sup.III.sub.2 each represents a hydrogen
atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group,
A.sup.III represents
##STR5##
wherein R.sup.III.sub.3 and R.sup.III.sub.9 each represents a hydrogen
atom, an alkyl group, a nitro group, a halogen atom, or a cyano group; and
m" and n" each represents an integer of 0 to 3.
Inventors:
|
Akasaki; Yutaka (Kanagawa, JP);
Nukada; Katsumi (Kanagawa, JP);
Sato; Katsuhiro (Kanagawa, JP)
|
Assignee:
|
Fuji Xerox Co., Ltd. (Tokyo, JP)
|
Appl. No.:
|
436617 |
Filed:
|
November 15, 1989 |
Foreign Application Priority Data
| Nov 16, 1988[JP] | 53-287615 |
| Nov 16, 1988[JP] | 53-287616 |
| Nov 16, 1988[JP] | 53-287619 |
Current U.S. Class: |
430/58.25; 430/58.35; 430/95 |
Intern'l Class: |
G03G 005/14 |
Field of Search: |
430/95,58,59
|
References Cited
U.S. Patent Documents
4106934 | Aug., 1978 | Turnblom | 430/58.
|
Foreign Patent Documents |
48-9988 | Mar., 1973 | JP.
| |
54-30834 | Mar., 1979 | JP.
| |
Primary Examiner: Welsh; David
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett and Dunner
Claims
What is claimed is:
1. An electrophotographic photoreceptor comprising a conductive substrate
having thereon a photosensitive layer wherein the photosensitive layer
comprises a charge generating material and at least one compound selected
from the group consisting of a compound of formula (I), a compound of
formula (II), and a compound of formula (III):
##STR19##
wherein X.sup.I represents a cyano group, an alkoxycarbonyl group, or an
aryloxycarbonyl group, R.sub.1.sup.I and R.sub.2.sup.I each represents a
hydrogen atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group, A.sup.I represents
##STR20##
wherein R.sub.3.sup.I to R.sub.9.sup.I each represents a hydrogen atom, an
alkyl group, a nitro group, a halogen atom, or a cyano group, and m and n
each represents an integer of 0 to 3;
##STR21##
wherein X.sup.II represents O, C(CN).sub.2 or C(CO.sub.2 R.sup.II).sub.2,
wherein R.sup.II is an alkyl group, R.sub.1.sup.II and R.sub.2.sup.II each
represents a hydrogen atom, an alkyl group, an aryl group, an
alkoxycarbonyl group, an aryloxycarbonyl group, a nitro group, a halogen
atom, or a cyano group, and m' and n' each represents an integer of 0 to
2; and
##STR22##
wherein R.sub.1.sup.III and R.sub.2.sup.III each represents a hydrogen
atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkoxycarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group, A.sup.III represents
##STR23##
wherein R.sub.3.sup.III and R.sub.9.sup.III each represents a hydrogen
atom, an alkyl group, a nitro group, a halogen atom, or a cyano group, and
m" and n" each represents an integer of 0 to 3.
2. The electrophotographic photoreceptor as claimed in claim 1, wherein the
photosensitive layer additionally comprises a binder resin in which a
ratio of said compound to the binder resin is from about 1/20 to about
20/1.
3. The electrophotographic photoreceptor as claimed in claim 2, wherein the
ratio between said compound to the binder resin is about 3/10 to 3/2.
4. The electrophotographic photoreceptor as claimed in claim 1, wherein the
photosensitive layer additionally comprises a binder resin.
5. The electrophotographic photoreceptor as claimed in claim 1, wherein the
photosensitive layer comprises a charge generating layer and a charge
transporting layer.
6. The electrophotographic photoreceptor as claimed in claim 5, wherein the
charge generating layer has a thickness of from about 0.05 to about 10
microns and the charge transporting layer has a thickness of from about 2
to about 100 microns.
7. The electrophotographic photoreceptor as claimed in claim 6, wherein the
charge generating layer has a thickness of from about 0.05 to about 5
microns and the charge transporting layer has a thickness of from about 10
to about 30 microns.
8. The electrophotographic photoreceptor as claimed in claim 1, wherein for
the compounds of formulas (I), (II), and (III), the alkyl group has from 1
to 10 carbon atoms, the aryl group has from 6 to 25 carbon atoms, the
alkoxycarbonyl group has from 2 to 11 carbon atoms, the aryloxycarbonyl
group has from 7 to 26 carbon atoms, the arylcarbonyl group has from 7 to
26 carbon atoms, and the alkylcarbonyl group has from 2 to 11 carbon
atoms.
9. A photosensitive layer useful in an electrophotographic photoreceptor
comprising a compound of formula (I), (II), or (III) as set forth in claim
1.
10. The electrophotographic photoreceptor as claimed in claim 1, wherein
the photosensitive layer is of a single layer type.
Description
FIELD OF THE INVENTION
The present invention relates to an electrophotographic photoreceptor for
forming an electrostatic latent image.
BACKGROUND OF THE INVENTION
Research has been conducted on an electrophotographic photoreceptor
containing organic photoconductive materials because it offers several
advantages such as no environmental pollution, higher productivity, and
lower costs. There is a prior art electrophotographic photoreceptor which
comprises a photosensitive layer containing diphenyldicyanoethylene
derivatives as a sensitizer. Such an electrophotographic photoreceptor is
disclosed in, for example, JP-A-54-30834 (the term "JP-A" as used herein
means an "unexamined published Japanese patent application").
A problem with such use of organic photoconductive materials is present
that a material which absorbs visible light to generate a charge exhibits
poor charge retaining capacity; in contrast, a material which exhibits
good charge retaining capacity and excellent film forming properties
barely exhibits photoconductive properties by visible light.
To overcome such problems, use of a photosensitive layer of a laminate type
composed of a layer containing a charge generating agent which absorbs
visible light to generate charges and another layer containing a charge
transporting agent to transport the charges produced has been attempted.
Various charge generating agents and charge transporting agents have been
suggested. For example, when the charge transporting agent is the hole
transporting agent type, amine compounds, hydrazone compounds, pyrazoline
compounds, oxazole compounds, oxadiazole compounds, stilbene compounds, or
carbazole compounds may be used. Also, it is known that
2,4,7-trinitrofluorenone is an electron transporting agent type in the
charge transporting agent. In addition, JP-B-48-9988 (the term "JP-B" as
used herein means an "examined Japanese patent publication") and Canadian
Patent 912019 disclose a compound containing boron as a charge
transporting agent.
In prior art electrophotographic photoreceptors comprising a single
photosensitive layer containing organic photoconductive materials, a
completely practical sensitizer has not been found.
In a function separated type electrophotographic photoreceptor comprising
laminated photosensitive layers, it is preferred that a positive charged
type be used because the generation of ozone in Corotron is prevented, and
toner charges are controlled upon development. When an electrophotographic
photoreceptor is of the positive charged type, and when a charge
transporting agent is a hole transporting agent, it is necessary to use a
charge generating layer as an upper layer. However, because the custom is
to make the charge generating layer thin, the problem arises that such a
thin charge generating layer is insufficient to meet the mechanical
requirements of an electrophotographic photoreceptor. Also, it would be
commercially advantageous to improve the properties of a positive charged
type electrophotographic photoreceptor because otherwise it would be
necessary to devise a copying machine capable of using a negative charged
one.
On the other hand, there is a need for an electrophotographic photoreceptor
of a positive charged type in which a considerably thick charge
transporting layer constitutes the upper layer. To this end, it is
necessary to use a charge transporting layer containing charge
transporting agent having an electron transporting property. However,
among conventional charge transporting agents having an electron
transporting property, there are not known those which are fully
practical.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above-noted problems
inherent in the prior art.
Accordingly, an object of the present invention is to provide an
electrophotographic photoreceptor having excellent electrophotographic
properties.
Another object of the present invention is to provide a laminate type
electrophotographic photoreceptor which is used under a positive charged
state, and exhibits excellent electrophotographic properties.
The present inventors have discovered that when at least one compound
selected from the group consisting of a compound represented by formula
(I), a compound represented by formula (II), and a compound represented by
formula (III) is used as a sensitizer or a charge transporting agent, an
electrophotographic photoreceptor having excellent electrophotographic
properties can be obtained.
To achieve the above objects, the present invention provides an
electrophotographic photoreceptor comprising a conductive substrate having
thereon a photosensitive layer, wherein the photosensitive layer comprises
as a charge transporting agent at least one compound selected from the
group consisting of a compound of formula (I), a compound of formula (II),
and a compound of formula (III). The compound of formula (I) is as
follows:
##STR6##
wherein X.sup.I represents a cyano group, an alkoxycarbonyl group, or an
aryloxycarbonyl group; R.sub.1.sup.I and R.sub.2.sup.I each represents a
hydrogen atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group; and A.sup.1 represents
##STR7##
wherein R.sub.3.sup.I to R.sub.9.sup.I each represents a hydrogen atom, an
alkyl group, a nitro group, a halogen atom, or a cyano group; and m and n
each represents an integer of 0 to 3.
The compound of formula (II) is as follows:
##STR8##
wherein X.sup.II represents O, C(CN).sub.2 or C(CO.sub.2 R.sup.II).sub.2
(wherein R.sup.II is an alkyl group); R.sub.1.sup.II and R.sub.2.sup.II
each represents a hydrogen atom, an alkyl group, an aryl group, an
alkoxycarbonyl group, an aryloxycarbonyl group, a nitro group, a halogen
atom, or a cyano group; and m' and n' each represents an integer of 0 to
2.
The compound of formula (III) is as follows:
##STR9##
wherein R.sub.1.sup.III and R.sub.2.sup.III each represents a hydrogen
atom, an alkyl group, an aryl group, an alkoxycarbonyl group, an
aryloxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, a
nitro group, a halogen atom, or a cyano group; and A.sup.III represents
##STR10##
wherein R.sub.3.sup.III to R.sub.9.sup.III each represents a hydrogen
atom, an alkyl group, a nitro group, a halogen atom, or a cyano group; and
m" and n" each represents an integer of 0 to 3.
For the compounds of formulas (I), (II), and (III), the alkyl group
described above preferably has 1 to 10 carbon atoms; the aryl group
described above preferably has 6 to 25 carbon atoms; the alkoxycarbonyl
group described above preferably has 2 to 11 carbon atoms; the
aryloxycarbonyl group described above preferably has 7 to 26 carbon atoms;
the arylcarbonyl group described above preferably has 7 to 26 carbon
atoms; and the alkylcarbonyl group described above has 2 to 11 carbon
atoms.
DETAILED DESCRIPTION OF THE INVENTION
Examples of the compounds represented by formula (I) include but are not
limited to the following:
##STR11##
Of the compounds represented by formulae I-(1) to I-(25), the compound of
formula I-(20) is preferred.
These compounds represented by formula (I) can be readily obtained as shown
in the following reaction equation. In particularly, compounds represented
by formula (Io) and malonitrile are heated under reflux in a solvent such
as pyridine to form compounds represented by formula (I'o) which, if
desired, are hydrolyzed, and undergo esterification or undergo
condensation with malonic acid ester, thereby forming the compounds
represented by formula (I).
##STR12##
wherein R.sub.1.sup.I, R.sub.2.sup.I, A.sup.I, X.sup.I, m, and n are
previously defined in formula (I).
The following examples illustrate the various methods to prepare the
compounds represented by formula (I). Although, only a few of the
compounds encompassed by formula (I) are illustratively prepared below,
method similar to the methods described below can be used to synthesize
the other compounds of formula (I).
I. Synthesis examples involving compounds of formula (I)
I-A. Synthesis of compound I-(20).
A compound having the following formula was made by a condensation reaction
between p-nitrobenzoyl chloride and diphenylmethane:
##STR13##
Into a 100 ml, three-necked, flask were poured 10.0 g (21.4 mmol) of the
compound thus prepared above, 5.7 g (85.8 mmol) of malonitrile, and 80 ml
of pyridine. The reaction mixture was refluxed in a stream of nitrogen for
3 hours, followed by removal of the pyridine under reduced pressure. The
residue was dissolved in methylene chloride, and then washed with
successive, dilute hydrochloric acid, and water, followed by drying with
Na.sub.2 SO.sub.4. The dried product was then purified by the use of a
short column of silica gel (in which methylene chloride was used as a
solvent). After removal of the solvent, recrystallization from ethyl
acetate gave 5.3 g (a 44.1% yield) of the compound I-(20) as light pink
acicular crystals, the melting point of which was 226.degree. to
228.degree. C.
I-B. Synthesis of compound I-(2).
Compounds I-(2) was produced as light yellow tabular crystals in the same
manner as in synthesis example I-A except that a compound having the
following formula, which was produced by a condensation reaction between
terephthaloyl chloride and n-butylbenzene, was used:
##STR14##
The compound I-(2) thus produced had a melting point of 201.degree. to
202.5.degree. C.
I-C. Synthesis of compound I-(13).
Compound I-(13) was produced as light yellow powders in the same manner as
in synthesis example I-A except that a compound having the following
formula, which was produced by a condensation reaction between
2,2'-dinitrobiphenyl-4,4'-carboxylic acid chloride and n-butylbenzene, was
used:
##STR15##
The compound I-(13) thus produced had a melting point of 231.degree. to
232.degree. C.
Examples of the compounds represented by formula (II) include but are not
limited to the following:
##STR16##
Of the compounds represented by formulae II-(1) to II-(19), the compound of
formula II-(1) is preferred.
The compounds represented by formula (II) can be synthesized by various
methods. For example, the compounds wherein X.sup.II is C(CN).sub.2 can be
synthesized by treating xanthone derivatives with thionyl chloride,
followed by reaction with malonitrile. The compounds in which X.sup.II is
C(CO.sub.2 R.sup.II).sub.2 can be made by hydrolyzing a compound wherein
X.sup.II is C(CN).sub.2, followed by esterification.
The following is a synthesis example illustrating the preparation of a
compound of formula (II). However, although only one of the compounds
encompassed by formula (II) is illustratively prepared below, methods
similar to the method described can be used to synthesize the other
compounds of formula (II).
II. Synthesis example involving a compound of formula (II)
II-A. Synthesis of compound II-(1).
Into a 200 ml round-bottomed flask were placed 20 g of xanthone and 100 ml
of thionyl chloride. The reaction mixture was stirred under a stream of
nitrogen for 3 hours, followed by removal of the thionyl chloride under
reduced pressure. To the residue was added 10 g of malonitrile. This
mixture was heated to 100.degree. C for one hour with vigorous stirring,
followed by cooling, and by dissolving the mixture in methylene chloride.
The resulting methylene chloride solution was purified by the use of a
short column of silica gel, followed by removal of the methylene chloride
under reduced pressure. The residue was washed twice with small amounts of
cold ethyl acetate. Finally, recrystallization from toluene gave 15.1 g (a
yield of 61%) of compound II-(1) as yellow powders, a melting point of
252.degree.-255.degree. C.
Examples of the compounds represented by formula (III) include but are not
limited to the following:
##STR17##
Of the compounds represented by formulae III-(1) to III-(24), the compound
of formulae III-(12) and III-(19) are preferred.
The compound represented by formula (III) can be synthesized by various
methods. For example, the compound wherein A.sup.III is constituent (1) or
constituent (2) of formula (III) can be produced by a condensation
reaction between terephthaloyl chloride derivatives or
biphenyl-4,4'-dicarboxylic acid chloride derivatives and benzene
derivatives. The compound wherein A.sup.III is constituent (3) of formula
(III) can be synthesized by a condensation reaction between
diphenylmethane derivatives and benzoyl chloride derivatives. Oxidation of
the compound yields constituent (4) of formula (III).
The following examples illustrate the various methods to prepare the
compounds represented by formula (III). Although only a few of the
compounds encompassed by formula (III) are illustratively prepared below,
methods similar to the methods described below can be used to synthesize
the other compounds of formula (III).
III. Synthesis examples involving compounds of formula (III)
III-A. Synthesis of compound III-(19).
Into a 500 ml, three-necked, flask were placed 25.0 g (135 mmol) of
p-nitrobenzoyl chloride, 20.0 g (150 mmol) of aluminum chloride, and 200
ml of methylene chloride. The mixture was stirred at -10.degree. C. under
a stream of nitrogen for 5 hours. A solution consisting of 9.25 g (55
mmol) of diphenylmethane and 50 ml of methylene chloride was slowly added
dropwise over a period of about 40 minutes to the reaction mixture,
followed by stirring for 2 hours. The mixture was stirred at room
temperature for 15 hours and 10.0 g (75 ml) of aluminum chloride was added
thereto, followed by refluxing for 24 hours. The reaction mixture was
cooled and then was added to 300 g of ice. A 20% by weight of an aqueous
potassium hydroxide solution was added to the reaction mixture until the
aluminum hydroxide was dissolved. The organic layers were separated and
the water phases were extracted with methylene chloride. All organic
phases were collected and the solvent was removed under reduced pressure,
followed by addition of about 300 ml of a 7% by weight of an aqueous
potassium hydroxide solution. The mixture was heated for about one hour at
about 70.degree. C. on a water bath to decompose acid chlorides. The
resulting precipitates were filtered off, and washed with ethyl acetate,
thereby obtaining light yellow powders. Finally, recrystallization from
ethanol and methylene chloride gave 11.8 g (a yield of 46.0%) of compound
III-(19), a melting point of 193.degree. to 195.degree. C.
III-B. Synthesis of compound III-(2).
Into a 500 ml, three-necked, flask were placed 25.0 g (123 mmol) of
terephthaloyl chloride, 40.0 g (300 mmol) of aluminum chloride, and 200 ml
of methylene chloride. The mixture was stirred at -10.degree. C. under a
stream of nitrogen for 5 hours. A solution consisting of 35 g (261 mmol)
of n-butylbenzene and 50 ml of methylene chloride was slowly added
dropwise over a period of about one hour to the reaction mixture, followed
by stirring for 30 minutes. To ice (200 g) was added the reaction mixture.
A 20% by weight of an aqueous potassium hydroxide solution was added to
the reaction mixture until the aluminum hydroxide was dissolved. The
organic phases were separated and the water phases were extracted with
methylene chloride. All organic layers were collected, and dried with
Na.sub.2 SO.sub.4, followed by removal of the solvent under reduced
pressure.
Finally, recrystallization of the residue from ethanol gave 39.0 g (a yield
of 79.4%) of compound III-(2) as colorless tabular crystals, a melting
point of 111.degree. to 112.degree. C.
III-C. Synthesis of compound III-(12).
Into a 500 ml, three-necked, flask were placed 20 g (60.2 mmol) of a
dicarboxylic acid having the following formula and 220 ml of thionyl
chloride.
##STR18##
The reaction mixture was refluxed in a stream of nitrogen for 24 hours,
followed by removal of the thionyl chloride. 50 ml of 1,2-dichloroethane
was added to the reaction mixture, and the remained thionyl chloride was
removed, thereby obtaining chlorides of the dicarboxylic acid as crude
products.
To the chlorides of dicarboxylic acid were added 33 g (248 mmol) of
aluminum chloride and 200 ml of methylene chloride, followed by stirring
at -20.degree. C. under a stream of nitrogen for 5 hours. A solution
consisting of 17.4 g (130 mmol) of n-butylbenzene and 30 ml of methylene
chloride was added dropwise to the reaction mixture for about 15 minutes.
The mixture was stirred at room temperature for 15 hours. To ice (200 g)
was added the reaction mixture. A 20% by weight of an aqueous potassium
hydroxide solution was then added to the reaction mixture until the
aluminum hydroxide was dissolved. The organic phases were separated and
the water phases were extracted with methylene chloride. All organic
layers were collected, and dried with Na.sub.2 SO.sub.4. The dried product
was then purified by the use of a short column of silica gel (in which
methylene chloride was used as a solvent). After removal of the solvent
under reduced pressure, recrystallization of the residue from methylene
chloride and methanol was carried out. Further recrystallization from
acetone and ethanol gave 17.3 g (51% yield) of compound III-(12) as light
yellow acicular crystals, the melting point of 115.degree. to
116.5.degree. C.
In the electrophotographic photoreceptor of the present invention, the
conductive substrate can be, for example, a metal pipe, a metal plate, a
metal sheet, a metal film (foil), a polymer film conductive-treated, a
polymer film provided with an evaporation layer of metal such as Al, metal
oxides such as SnO.sub.2, or a polymer film or paper coated with
quaternary ammonium salts.
In the electrophotographic photoreceptor of the present invention, a
photosensitive layer is formed on the conductive substrate. The
photosensitive layer can be a single layer type, or a laminate layer type
comprising a charge generating layer and a change transporting layer. A
photosensitive layer of a single layer type includes, for example, a
photosensitive layer comprising conventional materials such as
polyvinylcarbazole and containing at least one of the compounds of formula
(I), (II), or (III) as a sensitizer; or a photosensitive layer comprising
a binder resin layer containing a conventional charge generating agent and
containing at least one of the compounds of formula (I), (II), or (III) as
an electron transporting agent.
In a laminated photosensitive layer, the charge generating layer can be
obtained by various methods. For examples, the charge generating layer can
be obtained by vapor-depositing a charge generating agent on a conductive
substrate. Also, the charge generating layer can be formed by coating a
solution containing a charge generating agent and a binder resin as main
components on a conductive substrate. Any conventional charge generating
agents and binder resins can be used. Suitable charge generating agents
include inorganic semiconductor materials such as tri-Se, organic
semiconductor materials such as polyvinyl carbazole, bis-azo compounds,
tris-azo type compounds, phthalocyanines, pyrylium compounds, and organic
pigments such as squarylium compounds. Suitable binder resins include
polystyrenes, silicone resins, polycarbonate resins, acryl resins,
methacrylate resins, polyesters, vinyl polymer, celluloses, and alkyd
resins.
The thickness of the charge generating layer is from about 0.05 to 10
microns and preferably from about 0.05 to 5 microns.
The charge transporting layer is formed on the charge generating layer. The
charge transporting layer comprises at least one of compounds represented
by formula (I), (II), or (III) and a binder resin. In particular, the
charge transporting layer is formed by coating on a charge generating
layer a solution comprising at least one of compounds represented by
formula (I), (II), or (III), a binder, and suitable solvents by the use of
applicators, bar coaters, dip coaters, etc.
For photosensitive layers of both the single layer type and the laminate
type, it is preferred that the ratio of the compound of formula (I), (II),
or (III) to the binder resin is from about 1/20 to about 20/1 and most
preferably from about 3/10 to 3/2.
The binder resin used in the charge transporting layer, can be of any
conventional type. Examples of binder resins include styrene/butadiene
copolymers, vinyltoluene/styrene copolymers, styrene modified alkyd
resins, silicone modified alkyd resins, soybean oil modified alkyd resins,
vinylidene chloride/vinyl chloride copolymers, polyvinyl butyrals,
nitrated polystyrenes, polymethylstyrenes, polyisobutylenes, polyesters,
phenolic resins, ketone resins, polyamides, polycarbonates,
polythiocarbonates, polyvinyl haloallylates, vinyl acetate resins,
polystyrenes, polyvinylacrylates, polysulfones, and polymethacrylates.
In a preferred embodiment, an electron donating material may be added to
the charge transporting layer.
The thickness of the charge transporting layer is from about 2 to about 100
microns and preferably from about 10 to about 30 microns.
In the electrophotographic photoreceptor of the present invention, a
barrier layer may be formed on the conductive substrate. The barrier layer
prevents an injection of an undesirable charge from the conductive
substrate and thus improves picture quality. The barrier layer can be made
of such materials such as metal oxides (e.g., aluminum oxide), acrylic
resins, phenolic resins, polyester resins, or polyurethanes.
The present invention will be illustrated in more detail by the following
Examples.
EXAMPLES
Example I-1
A charge generating layer (2.5 microns) comprising trigonal system
selenium/polyvinylcarbazole (trigonal system selenium content: 7% by
volume) was formed on a conductive substrate. A solution made by
dissolving 0.5 g of Compound I-(2) and 0.75 g of bisphenol A polycarbonate
(Makrolon 5705 produced by Bayer Co.) in 7 g of methylene chloride was
coated thereon in a wet thickness of 5 mil (i.e., a gap: 5 mil), and was
then dried for one hour at 80.degree. C., thereby obtaining an
electrophotographic photoreceptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring sensitivity (dv/dt). The results
were as follows:
______________________________________
Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
85 --
______________________________________
Examples I-2 to I-10
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example I-1 except that compounds represented by the above formulae I-(3),
I-(4), I-(8), I-(11), I-(13), I-(18), I-(20), I-(22), and I-(24) were used
in place of Compound I-(2). The results are shown in Table I-1.
Comparative Example I-1
A sample of electrophotographic photoreceptor was produced and its
sensitivity was measured, respectively, in the same manner as in Example
I-1 except that 2,4,7-trinitrofluorenone (TNF) was used in place of
Compound I-(2). The result is shown in Table I-1.
TABLE I-1
______________________________________
Compound Added
(Compound) Initial Sensitivity
No. +800 V - 800 V
______________________________________
Example I-2 I-(3) 215 --
Example I-3 I-(4) 253 --
Example I-4 I-(8) 203 --
Example I-5 I-(11) 198 --
Example I-6 I-(13) 175 --
Example I-7 I-(18) 154 --
Example I-8 I-(20) 534 --
Example I-9 I-(22) 431 --
Example I-10
I-(24) 213 --
Comparative I-1
TNF 66 --
Example
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Example I-11
A solution made by dissolving 0.5 g of Compound I-(2) and 0.75 g of
polyvinylcarbazole in 7 g of methylene chloride was coated on a conductive
substrate in a wet thickness of 5 mil (i.e., a gap: 5 mil), and was then
dried for one hour at 80.degree. C., thereby obtaining an
electrophotographic photoreceptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring the sensitivity (dv/dt). The
results were as follows:
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Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
195 164
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Examples I-12 to I-20
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example I-11 except that compounds represented by the above formula I-(3),
I-(4), I-(8), I-(11), I-(13), I-(18), I-(20), I-(22), and I-(24) were used
in place of Compound I-(2). The results are shown in Table I-2.
Comparative Example I-2
A sample of electrophotographic photoreceptor was produced and its
sensitivity was measured, respectively, in the same manner as in Example
I-11 except that 2,4,7-trinitrofluorenone (TNF) was used in place of
Compound I-(2). The result is shown in Table I-2.
TABLE I-2
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Compound Added
(Compound) Initial Sensitivity
No. +800 V -800 V
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Example I-12
I-(3) 352 159
Example I-13
I-(4) 385 178
Example I-14
I-(8) 401 181
Example I-15
I-(11) 350 181
Example I-16
I-(13) 255 162
Example I-17
I-(18) 212 154
Example I-18
I-(20) 575 193
Example I-19
I-(22) 529 172
Example I-20
I-(24) 314 185
Comparative I-2
TNF 154 165
Example
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As is apparent from a comparison between Examples I-1 to I-20 and
Comparative Examples I-1 to I-2, the compounds of formula (I) which are
used in the present invention exhibit greatly improved charge transporting
ability as compared with TFN which is already known as having good change
transporting ability. Accordingly, the electrophotographic photoreceptors
containing the compounds of formula (I) exhibit excellent
electrophotographic properties. In particular, when the compounds of
formula (I) are used as charge transporting agents in the charge
transporting layer of a laminate type electrophotographic photoreceptor, a
positive charged type electrophotographic photoreceptor having excellent
electrophotographic properties can be obtained.
Example II-1
A charge generating layer (2.5 microns) comprising trigonal system
selenium/polyvinylcarbazole (trigonal system selenium content: 7% by
volume) was formed on a conductive substrate. A solution made by
dissolving 0.5 g of Compound II-(1) and 0.75 grams of bisphenol A
polycarbonate (Makrolon 5705 by Bayer Co.) in 7 g of methylene chloride
was coated thereon in a wet thickness of 5 mil (i.e., a gap: 5 mil), and
was then dried for one hour at 80.degree. C., thereby obtaining an
electrophotographic photoreceptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring sensitivity (dv/dt). The results
were as follows:
______________________________________
Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
93 --
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Examples II-2 to II-4
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example II-1 except that compounds represented by the above formulae
II-(3), II-(9), and II-(13) were used in place of Compound II-(1). The
results are shown in Table II-1.
Comparative Example II-1
A sample of electrophotographic photoreceptor was produced, and its
sensitivity was measured, respectively, in the same manner as in Example
II-1 except that 2,4,7-trinitrofluorenone (TNF) was used in place of
Compound II-(1). The result is shown in Table II-1.
TABLE II-1
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Compound Added
(Compound) Initial Sensitivity
No. +800 V -800 V
______________________________________
Example II-2
I-(3) 82 --
Example II-3
I-(9) 115 --
Example II-4
I-(13) 71 --
Comparative II-1
TNF 66 --
Example
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Example II-5
A solution made by dissolving 0.5 g of Compound II-(1) and 0.75 g of
polyvinylcarbazole in 7 g of methylene chloride was coated on a conductive
substrate in a wet thickness of 5 mil (i.e., a gap: 5 mil), and was then
dried for one hour at 80.degree. C., thereby obtaining an
electrophotographic photoreseptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring sensitivity (dv/dt). The results
were as follows:
______________________________________
Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
195 184
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Examples II-6 to II-8
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example II-5 except that compounds represented by the above formulae
II-(3), II-(9), and II-(13) were used in place of Compound II-(1). The
results are shown in Table II-2.
Comparative Example II-2
An electrophotographic photoreceptor was produced and its sensitivity was
measured, respectively, in the same manner as in Example II-5 except that
2,4,7-trinitrofluorenone (TNF) was used in place of Compound II-(1). The
result is shown in Table II-2.
TABLE II-2
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Compound Added
(Compound) Initial Sensitivity
No. +800 V -800 V
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Example II-6
I-(3) 175 170
Example II-7
I-(9) 234 184
Example II-8
I-(13) 169 152
Comparative II-2
TNF 154 165
Example
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As is apparent from a comparison between Examples II-1 to II-S and
Comparative Examples II-1 to II-2, the compounds of formula (II) which are
used in the present invention exhibit greatly improved charge transporting
ability as compared with TNF which is already known as having good charge
transporting ability. Accordingly, the electrophotographic photoreceptors
containing the compounds of formula (II) exhibit excellent
electrophotographic properties. In particular, when the compounds of
formula (II) are used as charge transporting agents in the charge
transporting layer of a laminate type electrophotographic photoreceptor, a
positive charged type electrophotographic photoreceptor having excellent
electrophotographic properties can be obtained.
Example III-1
A charge generating layer (2.5 microns) comprising trigonal system
selenium/polyvinylcarbazole (trigonal system selenium content: 7% by
volume) was formed on a conductive substrate. A solution made by
dissolving 0.5 g of Compound III-(2) and 0.75 g of in 7 g of methylene
chloride was coated thereon in a wet thickness of 5 mil (i.e., a gap: 5
mil), and was then dried for one hour at 80.degree. C., thereby obtaining
an electrophotographic photoreceptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring sensitivity (dv/dt). The results
were as follows:
______________________________________
Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
84 --
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Examples III-2 to III-9
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example III-1 except that compounds represented by the above formulae
III-(3), III-(4), III-(10), III-(12), III-(17), III-(19), III-(21), and
I-(24) were used in place of Compound III-(2). The results are shown in
Table III-1.
Comparative Example III-1
An electrophotographic photoreceptor was produced and its sensitivity was
measured, respectively, in the same manner as in Example III-1 except that
2,4,7-trinitrofluorenone (TNF) was used in place of Compound III-(2). The
result is shown in Table III-1.
TABLE III-1
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Compound Added
(Compound) Initial Sensitivity
No. +800 V -800 V
______________________________________
Example III-2
III-(3) 175 --
Example III-3
III-(4) 189 --
Example III-4
III-(10) 165 --
Example III-5
III-(12) 154 --
Example III-6
III-(17) 193 --
Example III-7
III-(19) 254 --
Example III-8
III-(21) 234 --
Example III-9
III-(24) 147 --
Comparative III-1
TNF 66 --
Example
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Example III-10
A solution made by dissolving 0.5 g of Compound III-(2) and 0.75 g of
polyvinylcaraozole in 7 g of methylene chloride was coated on a conductive
substrate in a wet thickness of 5 mil, and was then dried for one hour at
80.degree. C., thereby obtaining an electrophotographic photoreceptor.
Using an electrostatic copying paper testing device ("SP428" produced by
Kawaguchi Denki Manufacturing Co., Ltd.), the electrophotographic
photoreceptor was charged to +800 V and -800 V, and was then exposed to a
white light of 5 luxes, thereby measuring the sensitivity (dv/dt). The
results were as follows:
______________________________________
Charged Potential +800 V -800 V
Initial Sensitivity (V/sec)
174 171
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Examples III-11 to III-18
Samples of electrophotographic photoreceptors were produced and their
sensitivities were measured, respectively, in the same manner as in
Example III-10 except that compounds represented by the above formula
III-(3), III-(4), III-(10), III-(12), III-(17), III-(19), III-(21), and
III-(24) were used in place of Compound III-(2). The results are shown in
Table III-2.
Comparative Example I-2
An electrophotographic photoreceptor was produced and its sensitivity was
measured, respectively, in the same manner as in Example III-10 except
that 2,4,7-trinitrofluorenone (TNF) was used in place of Compound III-(2).
The result is shown in Table III-2.
TABLE III-2
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Compound Added
(Compound) Initial Sensitivity
No. +800 V -800 V
______________________________________
Example III-11
III-(3) 205 183
Example III-12
III-(4) 234 162
Example III-13
III-(10) 172 154
Example III-14
III-(12) 155 163
Example III-15
III-(17) 206 170
Example III-16
III-(19) 305 155
Example III-17
III-(21) 298 159
Example III-18
III-(24) 162 175
Comparative III-2
TNF 154 165
Example
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As is apparent from a comparison between Examples III-1 to III-18 and
Comparative Examples III-1 to III-2, the compounds of formula (III) which
are used in the present invention exhibit greatly improved charge
transporting ability as compared with TFN which is already known as having
good change transporting ability. Accordingly, the electrophotographic
photoreceptors containing the compounds of formula (III) exhibit excellent
electrophotographic properties. In particular, when the compounds of
formula (III) are used as charge transporting agents in the charge
transporting layer of a laminate type electrophotographic photoreceptor, a
positive charged type electrophotographic photoreceptor having excellent
electrophotographic properties can be obtained.
While the invention has been described in detail and with reference to
specific embodiments thereof, it will be apparent to one skilled in the
art that various changes and modifications can be made therein without
departing from the spirit and scope thereof.
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